Re: D4, maybe "distinguished"... or "stout"... "diminutive", or "exceeding all reasonable expectations". But yeah "sleek" would be a stretch.
The problem is that you want ramping feature on a tail clicky light, when that's apparently a momentary/ always on switch type feature... So you need a driver that supports Toy Keeper's Crescendo firmware, which is a ramping UI made for Clicky switches!
There are a few of them on Mountain Electronics; find the diameter drive required for the Convoy S2+ that has Crescendo as an option and you're almost there